Upd.: in (1), there should be exp in the sum as well (so that the transition probabilities sum to 1). Already uploaded the corrected version to docdroid.

Thanks for the update. You described an interesting tip selection algorithm. Probably it makes a lot of sense. It makes lazy tips (nice term btw) less likely to be confirmed. However those lazy tips can still be connected to the recent part of the DAG by interested parties. I'm not sure though, that we are considering exactly the same scenario.The first question. On fig. 1 you placed the second doublespending transaction not to the root of the parasitic subtangle but significantly higher. So the question is: is there a reason why the attacker would want to accumulate PoW not above but below the second doublespending transaction?The second question. When the attacker reveals his parasitic subtangle, the resulting united tangle contains two contradicting transactions (the doublespends). And the second doublespend (included in the parasitic subtangle) has much more PoW confirming it. So is it just a matter of tip selection? Or should the first doublespend and all transactions depending on it be excluded from the DAG at this point?P.S. "Excluded from the DAG" isn't the right phrase. I meant shouldn't they be excluded from candidates for confirmation, because they confirm the less confirmed doublespend?

Upd.: in (1), there should be exp in the sum as well (so that the transition probabilities sum to 1). Already uploaded the corrected version to docdroid.

Thanks for the update. You described an interesting tip selection algorithm. Probably it makes a lot of sense. It makes lazy tips (nice term btw) less likely to be confirmed. However those lazy tips can still be connected to the recent part of the DAG by interested parties. I'm not sure though, that we are considering exactly the same scenario.The first question. On fig. 1 you placed the second doublespending transaction not to the root of the parasitic subtangle but significantly higher. So the question is: is there a reason why the attacker would want to accumulate PoW not above but below the second doublespending transaction?The second question. When the attacker reveals his parasitic subtangle, the resulting united tangle contains two contradicting transactions (the doublespends). And the second doublespend (included in the parasitic subtangle) has much more PoW confirming it. So is it just a matter of tip selection? Or should the first doublespend and all transactions depending on it be excluded from the DAG at this point?P.S. "Excluded from the DAG" isn't the right phrase. I meant shouldn't they be excluded from candidates for confirmation, because they confirm the less confirmed doublespend?

I think there is no way to prevent the attacker to publish a parasite chain that contains a double-spend that, at the moment, has more PoW in it than the legit tx. The idea is that the nodes won't select the attacker's tips, so his double-spend will eventually fall to limbo (and the legit tx will continue to gain weight), even if it had initially more cumulative weight. For that exact reason, the nodes won't use the rule "confirm the more confirmed double-spend", it's rather "the tip that I found first has the priority".

P.S. Probably, that means that the cumulative weights shouldn't be used to decide which tx is legit (at least for "not very old" transactions). Instead, just run the tip selection algorithm and see which of the two tx's it approves.

P.P.S. Sure, I should have moved the red tx to the beginning of the parasite chain, but, anyhow, that probably changes nothing due to the reasons exposed above.

P.S. Probably, that means that the cumulative weights shouldn't be used to decide which tx is legit (at least for "not very old" transactions). Instead, just run the tip selection algorithm and see which of the two tx's it approves.

That's quite a significant change to the design, which should be carefully thought over.

Can someone give few examples about why average Joe will buy IoT-device ? I'm sick of "countless examples" words without actual examples. Don't say countless, give an actual list of 10 or more examples.